Power operated hand tool



April 14, 1970 P. D. HOLDEN 3,505,733

PQWER OPERATED HAND TOOL Filed Oct. 9, 1967 42 I6 IO INVENTOR PETER D. HOLDEN ATTORNEY United States Patent O 3,505,733 POWER OPERATED HAND TOOL Peter D. Holden, Convent Station, N.J., assignor to Ingersoll-Rand Company, New York, N.Y., a corporation of New Jersey Filed Oct. 9, 1967, Ser. No. 673,547 Int. Cl. B23d 45/00; F16h 21/18 US. Cl. 30166 6 Claims ABSTRACT OF THE DISCLOSURE A power operated hand tool wherein a driven element, connected such that its transverse oscillation drives a working implement, is transversely oscillated by eccentrics through roller bearings and cooperating arcuate protrusions on the driven element.

BACKGROUND OF THE INVENTION The present invention relates to power operated tools and more particularly to power operated hand tools of the type wherein the rotary output of a driving means is converted into transverse oscillation of a driven element.

conventionally, power operated hand tools of the aforementioned type have sometimes employed an eccentric for converting the rotary output of the driving means into transverse oscillation of a driven element which drives the tool working implement. For example, United States Patent No. 3,256,758, issued June 21, 1966, to A. L. Medesha, and assigned to the assignee of the present invention, discloses an angle wrench of this general construction. These conventional tools are, of course, of obvious utility due to their relative simplicity and economy in construction.

However, the construction of these conventional tools has been found to permit relative slidable movement between the eccentric and the driven element. This relative slidable movement causes excessive wear which, if prolonged, can cause premature failure of the tools. This excessive wear is, of course, particularly acute in those instances in which the aforedescribed construction is applied to a tool, such as a surgical cast or bone cutting saw, wherein the driven element is oscillated at relatively high velocity.

The principal object of the present invention is to provide a new and improved power operated hand tool of the type set forth which is particularly constructed and arranged to substantially eliminate wear due to relative sliding between the eccentric and the driven element.

SUMMARY OF THE INVENTION The aforegoing object, and those other objects and advantages of the invention which will be apparent from the following description taken in connection with the accompanying drawings, are attained by the provision of a power operated hand tool in general comprising a driving means, and a driven element which includes an opening and is connected to a working implement such that its transverse oscillation drives the working implement. An eccentric means is disposed within the opening in the driven element and connected to the driving means to be rotatably driven by the latter; and a roller bearing means is circumferentially carried by the eccentric means within the opening. A wall of the opening is provided with an arcuate portion engaging the roller bearing means whereby rotation of the eccentri means causes the engaging roller bearing means and arcuate portion to effect transverse oscillation of the driven element.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial, elevational sectional view of a "ice surgical cast or bone cutting saw including an embodiment of the invention;

FIG. 2 is an enlarged, fragmentary, elevational sectional view of the saw illustrated in FIG. 1; and

FIG. 3 is a sectional view taken on line 33 of FIG. 2, looking in the direction of the arrows.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring more particularly to the drawings wherein similar reference characters designate corresponding parts throughout the several views, FIG. 1 illustrates a hand held, surgical cast or bone cutting saw designated generally as 10. The saw 10 comprises a housing for-med to include a rearward or motor carrying portion 12, a forward or working implement mounting portion 14, and an intermediate portion 16 connecting the portions 12, 14. The motor carrying portion 10 contains a conventional, vane type, pneumatically operated motor 18 which includes a rotor 20, a plurality of vanes 22 carried by the rotor 20, and a shaft-like extension 24 projecting from each of the opposing ends of the rotor 20'. The shaft-like extensions 24 are each formed integrally with the rotor 20 and rotatably mounted to permit rotation of the rotor 20. The pneumatically operated motor 18, as will be understood, is suitably connected in a conventional manner to a source (not shown) of pressurized air to receive pressurized air from such source upon the manual actuation of the trigger (not shown) of the saw 10.

The shaft-like extension 24 projecting from the forward end of the rotor 20 is spline connected at 26 to a driving shaft 28 which is rotatably mounted by a roller bearing 30. The driving shaft 28 projects into the intermediate housing portion 16 and carries therein a pair of eccentrics 32, 34 which, for the purposes of illustration, are shown in the drawings as being formed integrally with the driving shaft 28. The eccentrics 32, 34 are each formed of different diameter and are offset to the same side of the longitudinal axis of the driving shaft 28. The driving shaft 28 is rigidly connected by a mounting bolt 36 to a circumferential sleeve 38 which includes an integral balancing weight 40. The balancing weight 40 is offset to the opposing side of the longitudinal axis of the driving shaft 28 from the eccentrics 32, 34 and balances the latter to prevent the driving shaft 28 from wobbling during its rotation.

The working implement of the saw 10 comprises a circular saw blade 42 which is rigidly mounted upon one end of a mounting nut 44 rotatably supported by the forward end of the forward housing portion 14. The mounting nut 44 is rigidly connected to one end of a driven arm element 46, disposed within the housing, such that the saw blade 42 is reciprocated by transverse oscillation of the driven element 46. The driven element 46 is formed of fork configuration and comprises a trunk 48 which extends longitudinally in the forward housing portion 14 and a pair of branches 50, 52 which project into the intermediate housing portion 16 upon opposing sides of the eccentrics 32, 34. The trunk 48 of the driven element 46 is formed of essentialy skeletal construction to facilitate the lightness and portability of the saw 10. The branches 50, 52 are constructed of differential lengths such that the branch 50 is appreciably longer than the branch 52 and have their rearward ends terminating adjacent the eccentrics 34, 32, respectively. Thus, the eccentrics 32, 34 extends transversely to the longitudinal axis of the driven element 46 and are disposed within an opening 53 defined by the branches 50, 52.

The present invention, as applied to the saw 10, comprises the provision of new and improved means for connecting the eccentrics 32, 34 to the branches 50, 52 of the driven element 46 such that relative slidable movement of the eccentrics 32, 34 and the branches 50, 52 is substantially eliminated. Towards this end, as illustrated in FIGS. 1 and 2, a roller bearing 54 is positioned circumferentially around the eccentric 32 and a roller bearing 56 is positioned circumferential around the eccentric 34.

More particularly, the roller bearing 54 comprises an inner race 58 which is connected to the eccentric 32, an outer race '60 which circumferentially surrounds the inner race 58 in spaced relationship thereto, and a plurality of balls 62 located intermediate the races 58, 60 in engagement therewith. An annular wear sleeve 64 is aflixed cir- :umferentially around the outer race 60 to prevent wear of the latter. Similarly, the roller bearing 56 comprises an inner race 66 which is connected to the eccentric 34, an outer race 68 which surrounds the inner race 66 in spaced relationship thereto, and a plurality of balls 70 disposed intermediate the races 66, 68 in engaging relationship therewith. An annular wear sleeve 72, similar to the aforedescribed wear sleeve 64, is affixed circumferentially around the outer race 68 of the roller bearing 54 to prevent wear of the outer race 54. Lateral movement of the inner races 58, 66 is prevented by an annular shoulder 74 circumferentially formed on the driving shaft 28 immeliately rearwardly of the eccentric 34, an annular spacer :lement 76 positioned intermediate the roller bearings 54, 56, and an annular retaining member 78 fixedly mounted y a bolt 80 forwardly of the roller bearing 54.

The inner surface 82 of the branch 52 of the driven :lement 46 includes an integral protrusion 84, extending :ransversely throughout the width of the branch 52, which ongitudinally is formed of convex configuration. The pro- :rusion 84 is positioned adjacent the rearward end of he branch 52 opposite the roller bearing 54 and directly :ngages the annular wear sleeve 64 of the roller bearing 54. The inner surface 86 of the branch 50 of the driven :lernent 46, similarly, includes an integral protrusion 88, :xtending transversely throughout the width of the branch 50, which longitudinally is of convex configuration. The arotrusion 88 is positioned adjacent the rearward end of he branch 50 opposite the roller bearing 56 and directly :ngages the wear sleeve 72 of the roller bearing 56. The )recise radius of curvature of each of the protrusions 84, i8 is, of course, greatly dependent upon numerous variibles. However, it is believed that the radius of curvaure of each of the protrusions 84, 88 should be formed tccording to the following equation to obtain maximum lenefit from the aforedescribed construction.

vhere :the radius of curvature of the protrusion.

=distance rolled by the eccentric operatively engaging the protrusion in one-half of a revolution.

:amplitude of the oscillation of either of the driven element 46 or the saw blade 42.

Furthermore, it is believed that each of the eccentrics hould be constructed in accordance with the following quation.

here

=the diameter of the eccentric :the distance between the centerline of the driving shaft 28 and the centerline of the eccentric =distance rolled by the eccentric in one-half of a revolution :amplitude of the oscillation of either of the saw blade 42 or the driven element 46 k=minimum radial distance between the centerline of the driving shaft 28 and the extremities of the eccentric In the operation of the aforedescribed saw 10, rotation of the rotor 20 drives the driving shaft 28 to provide conjoined rotation of the eccentrics 32, 34. This rotation of the eccentrics 32, 34 causes the roller bearings 54, 56 to provide transverse oscillation of the driven element 46 which, in turn, causes rotary reciprocation of the saw blade 42. As the only engagement between the roller bearings 54, 56 and the branches 52, 50, respectively, occurs at the protrusions 84, 88, substantially all relative motion between the roller bearings 54, 56 and the branches 50, 52 occurs as rolling motion. Hence, relative slidable movement between the eccentrics 32, 34 and the branches 50', 52, and the wear associated therewith, is substantially eliminated.

From the aforegoing, it will be seen that I have provided new and improved means for accomplishing all of the objects and advantages of my invention. It will be understood, however, that, although I have hereinbefore illustrated and specifically described only one embodiment of my invention, my invention is not limited merely to this single embodiment but rather contemplates other embodiments and variations employing the concepts and teachings of my invention. For example, and not by way of limitation, it will be understood that, although the aforedescribed embodiment of my invention includes a pair of eccentrics, a single eccentric or more than two eccentrics, alternatively, could be employed.

Having thus described my invention, I claim:

1. A power operated hand tool comprising driving means, a driven element provided with walls bounding an opening, a working implement connected to said driven element to be driven by transverse oscillation of said driven element, eccentric means in said opening and connected to said driving means to be rotatably driven thereby, roller bearing means circumferentially carried by said eccentric means in said opening and provided with an arcuate outer periphery for engaging one of said walls bounding said opening, and said one of said walls including a convex protrusion engaging said arcuate outer periphery of said roller bearing means whereby rotation of said eccentric means acts through said engaging convex protrusion and arcuate outer periphery to provide transverse oscillation of said driven element.

2. A power operated hand tool according to claim 1, wherein said arcuate outer periphery is on a wear sleeve.

3. A power operated hand tool comprising driving means; a driven element provided with walls bounding an opening; a working implement connected to said driven element to be driven by transverse oscillation of said driven element; a plurality of eccentrics in said opening and connected to said driving means to be rotatably driven thereby; roller bearing means circumferentially carried by each of said eccentrics; said roller bearing means each comprising an inner race circumferentially mounted on one of said eccentrics, an outer race circumferentially around said inner race and radially spaced therefrom, and a plurality of rolling members rotatably disposed between said races in engagement therewith; said roller bearing means being provided with annular outer peripheries for engaging said walls of said opening; and said Walls of said opening having convex protrusions directly engaging said annular outer peripheries whereby rotation of said eccentrics acts through said engaging convex protrusions and annular outer peripheries to provide transverse oscillation of said driven element.

4. A power operated hand tool according to claim 3, wherein said annular outer peripheries are on wear sleeves mounted around said outer races, and said engagement of said convex protrusions and said annular outer peripheries is the sole engagement between said roller bearing means and said driven element.

5. A power operated hand tool according to claim 4, wherein said walls of said opening are of different lengths and each have one of said convex protrusions thereon, said eccentrics are disposed transversely to the longitudinal axis of said driven element, and said working implement comprises a cutting tool.

6. A power operated hand tool according to claim 3, wherein each of said convex protrusions is constructed to have a radius of curvature in accordance with the equation where r is said radius of curvature, f is the distance rolled by the respective eccentric in one-half of a revolution, and 6 is the amplitude of the movement of one of said driven element and said working implement.

References Cited UNITED STATES PATENTS ROBERT C. RIORDON, Primary Examiner 10 R. v. PARKER, JR., Assistant Examiner U.S. C1. X.R. 

